This invention relates to the straightening of damaged automobile underframes and door hinge pillars, and, more particularly, to pull clamps that attach to the frame structure of the automobile.
Automobile accidents produce damage of varying severity to the involved vehicles. In a relatively minor automobile accident of the "fenderbender" type, only the bodywork of the automobile is damaged. The automobile is repaired by replacing the damaged bodywork panels.
In more severe accidents, all or part of the frame of the automobile can be bent, in addition to the damage to the bodywork panels. To repair a bent frame, an external frame straightening puller is attached to the frame using a pull clamp. A sufficiently large pulling force is applied by the external puller to the pull clamp and thence to the frame, so that the frame is straightened back to its original form. Since the frame may be bent in a complex fashion, the straightening process usually involves an incremental series of attachments and straightening pulls at different locations of the frame. Once the frame is straightened, new bodywork panels and other components are attached to the frame to complete the repair.
Automobile manufacturers provide holes in the frame members of their products for assembly of the automobile, and also in anticipation of the need to attach a pull clamp during repair. For example, the door hinges of most automobiles are attached with bolts using a hole pattern on the door hinge pillar. When the door hinge pillar is to be straightened, the door hinge can be removed and a pull clamp attached through this hole pattern. In another example, the primary body underframe of an automobile having a unibody welded construction may have holes positioned in frame members primarily for use in straightening operations.
One of the problems faced by automotive repair services who perform frame straightening is that there are no standard patterns of attachment holes in automotive frames. For example, the patterns of holes in General Motors frames is typically different from that in Ford frames. Also, there are different arrangements of holes in various parts of the frames of even the same manufacturer. The hole patterns may also vary from year-to-year in the models of the same manufacturer.
Frame straightening repair services must therefore purchase multiple sets (sometimes termed "tool boards") of pull clamps that are operable for various hole patterns. Both a "General Motors Tool Board" and a "Ford Tool Board" would be purchased, as well as tool sets for other automobile manufacturers. An alternative to this expensive outlay is to jury rig pull clamps, which can lead to ineffective straightening procedures.
Another alternative is the use of pull clamps with multiple attachment hole configurations. Such pull clamps are typically in the form of a plate with multiple holes therein. The frame straightener attempts to find sets of holes in the plate that register with those of the frame. If such a registry can be found, the plate is attached through those holes, and the straightening force is applied by attachment to another location on the plate. This approach has limited effectiveness, because it is often difficult to find a registered pattern and because it is difficult to apply the straightening force in precisely the desired direction.
There is therefore a need for an improved approach to pull clamps for frame straightening of automobiles. The present invention fulfills this need, and further provides related advantages.